Or, put another way, trying to perfectly mate the underside of a 12 foot fabrication to a 6 foot wedge machined from a solid billet to within 1/100mm... twice!

1/100mm? Thought we weren't keen on base-ten flummery.
0.0003 inch, or 4 tenths, much more imperial. Pretty tight tolerance on a 1/2 in ground shaft let alone over 6ft. Can imagine temperature variations caused that 6ft lump to expand and contract well beyond that.

Talking of thous, I once had to show a young apprentice lad what a thou was, so I set up the anvils of a mike to 0.001, held it up to the daylight and said "thats one thou, how many of those do you think there are in an inch?" After pondering the question for a while he replied with "there must be millions"

1/100mm? Thought we weren't keen on base-ten flummery.
0.0003 inch, or 4 tenths, much more imperial. Pretty tight tolerance on a 1/2 in ground shaft let alone over 6ft.

MKW always quoted their planing wedge to be inside 1/100mm end to end so I never bothered to translate it into English as most people can only count to ten.
Our steering shaft was an interesting one. it was centreless-ground from three lengths of cold-drawn seamless hydraulic pipe to 0.9980" The man would only give me two thou clearance on the bearings and two of those were actually 0.998 themselves and had to be lapped before the shafting would slide but the tolerance on those shafts over about 18 ft was very impressive. Green & Preece grinding did it for us.

A friend of mine, blessed with a sharp mind, and even sharper sense of humour, was asked his opinion of who was right and wrong in a dispute between two people at work.
His reply was "Well , I think its 6 to the base 10 of one and 10 to the base 6 of the other...

Back in the 1970s in the early days of the dreaded decimalisation in the UK, I went to buy an eight foot length of timber, to be told that it was only sold by the metre. So I enquired how much it would cost and was advised " 15 pence a foot Mate"

My least favourite metric/imperial gotcha was the top skin for the air intakes. It would come out of a 8x4' sheet but in no way were we going to get it out of a 2x1m sheet. You'll never see it but that skin had to have a 4" strip welded on all the way across the front edge before we could begin wheeling it in.

Here John and me are dressing the weld.

Extending panel.jpg

It wheeled in perfectly after that.

Wheeling intake skin.jpg

You do not have the required permissions to view the files attached to this post.

I'm only a plumber from Cannock...

"As to reward, my profession is its own reward;" Sherlock Holmes.

I have wrought my simple plan
If I give one hour of joy
To the boy who’s half a man,
Or the man who’s half a boy.

Small Arms are fun measurement-wise. I think the best one is the FN FAL, of which there are two groups, Metric and Imperial (of which the British Armies SLR was one). Both groups fire the same ammunition, 7.62 NATO, a modification of the .300 Savage cartridge, also known as the .308 Winchester. The M16 and SA80 both fire a .22 inch round, the 5.56 NATO. Then there was the .280 British, originally termed a 0.270 in round, accepted into UK service as the 7mm Mk1Z which was actually, and always was, 0.284 in / 7.2 mm in diameter. A very few Metric FN FALs were built to shoot .280 British...